Cell therapy has emerged as a novel approach to enhance recovery from ischemic stroke. Animal stroke studies support the safety and efficacy of various types of cells derived from different tissues. Bone marrow cells may participate in natural processes of brain repair after neurological injury. Within the bone marrow reside mononuclear cells (MNCs) which contain multipotential stem cells and other cellular components that promote angiogenesis. Animal studies suggest that MNCs may improve outcome in various disorders including stroke, myocardial infarction, and head trauma. At UT-Houston, two clinical studies are currently assessing the safety of MNCs in pediatric head trauma and congestive heart failure. We proposed a phase IIa safety study in our SPOTRIAS program grant;however, the reviewers indicated that pivotal animal studies are still needed to determine important efficacy measures including dosing, optimal time after stroke for cellular administration, and best route of delivery. Our preliminary studies suggest that intra- arterial or intravenous administration of MNCs (10 million) to animals with ischemic stroke significantly reduces neurological deficits within 1 week after transplantation and the benefit is sustained 2 months after stroke, compared with vehicle-treated control animals. MNCs can be derived from a patient's own marrow and therefore represent an attractive therapeutic approach for autologous transplantation. This proposal therefore seeks to address key translational steps for the development of autologous bone marrow mononuclear cells (MNCs) as a novel therapy for ischemic stroke. Aim 1 will define a dose response, therapeutic time window, and optimal route of delivery of MNCs in the rodent model of reversible distal MCA occlusion causing cortical infarction and reperfusion injury. We have developed a rodent model that permits bone marrow harvest after stroke and MNC re-infusion of autologous cells. In Aim 2, using optimal conditions defined in Aim 1, we will determine efficacy of MNCs in other settings clinically important to stroke: aged animals, proximal MCA occlusion causing cortical and subcortical infarction, and permanent MCA occlusion. In Aim 3, we will determine the safety of MNCs following treatment with tissue plasminogen activator in an embolic stroke model. These aims will provide critical information that would be used to design a phase IIa safety study of MNCs in ischemic stroke patients at UT-Houston where there is already an extensive infrastructure to conduct clinical safety trials on cellular therapies. PUBLIC HEALTH RELEVANCE: Stroke is the leading cause of adult disability but there are few effective treatments for this devastating condition. Cell therapy is a promising new approach to enhance recovery from stroke. This application proposes critical experiments to test bone marrow mononuclear cells in clinically relevant animal models of stroke. The data from these proposed experiments are essential to design our first clinical safety study using these cells in stroke patients.